Recently I have noticed that the “stamina” of my Acer notebook’s battery has been getting progressively worse. The laptop is hardly a year old and yet I get only 3/4ths of the time I used to get with it when I bought it. I wanted to know more details about how my battery’s doing.
(img credit: Sean Dreilinger on Flickr)
To find out all the details you would want to know about you battery, browse to the directory
/proc/acpi/battery/ and then to the directory that has your battery in it.
Once there, see the contents of the files to learn more about your battery. Here’s what my files tell me:
So, as you can see, my battery does not charge to its full design capacity of 4400 mAh. It only charges to 3134 mAh, which is almost 3/4ths of the original capacity. Looks like my battery is on the downhill slide.
Since it is a Lithium Ion battery, I went looking for details on how to take good care of it. It is a good thing I did, because it demystified me - Letting your battery drain to “dead” before recharging it is not good. I really thought it was, but it is not. Wish I had known this earlier! I found an excellent page online with details of what factors affect the performance and lifespan on Lithium Ion batteries. The page includes graphs to show stored charge levels, temperature, discharge load etc affect battery longevity. In case you don’t have the time to read the page, here’s some points for you to remember to ensure a long life for your LiON battery:
- Avoid frequent discharges to 0% stored charge.
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- Several partial discharges with frequent recharges is better, since Lithium-Ion batteries have no “memory”
- You still have to allow it to go from full charge to near-empty charge once in 30 charge cycles to make sure that the battery charge monitor is properly calibrated
- Avoid Heat
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- Don’t leave the laptop in the car
- If you are going to use the laptop connected to power for a week or more continuously, take the battery out. This will save it from the heat and from the charge-discharge problems
- The batteries deteriorate even when they are stored cool!
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- Don’t buy a replacement battery or a spare battery until the time when you really need it!
- If you have to store a Lithium Ion battery - store it at 40% charge and store it in a refrigerator
Take care of your battery, because there is no way to restore capacity to failed batteries. Also, an average battery is good for 300-500 charge/discharge cycles, or about 1-2 years. The main physical reason for the degradation of performance seems to be increased internal resistance, which causes the battery to be unable to deliver the charge stored in it to the outside world (the internal resistance eats it up 
). Chemical decomposition of components also reduces the charge delivery capacity over time. So it is best to do the most you can to slow down the degradation by following the tips above.